Opioid abuse has increased in the last decade, primarily as a result of increased access to prescription opioids. Physicians are also increasingly administering opioid analgesics for noncancer chronic pain. Thus, knowledge of the long-term consequences of opioid use/abuse has important implications for fully evaluating the clinical usefulness of opioid medications. Many studies have examined th...

BACKGROUND Opioid use and dosing for patients with chronic non-cancer pain have dramatically increased over the past decade, resulting in a national epidemic of mortality associated with unintentional overdose, and increased risk of disability among injured workers. We assessed changes in opioid dosing patterns and opioid-related mortality in the Washington State (WA) workers' compensation syst...

mu-Opioid receptors are the pharmacological targets of endogenous opioid peptides and morphine-like alkaloid drugs. Previous studies of transfected cells and peripheral neurons indicate that opioid receptors are rapidly internalized after activation by the alkaloid agonist etorphine but not after activation by morphine. To determine whether opioid receptors in the central nervous system are reg...

Neuropeptides are essential for the regulation of appetite. Here we show that neuropeptides could regulate feeding in mutants that lack neurotransmission from the motor neurons that stimulate feeding muscles. We identified nlp-24 by an RNAi screen of 115 neuropeptide genes, testing whether they affected growth. NLP-24 peptides have a conserved YGGXX sequence, similar to mammalian opioid neurope...

The use of opioid agonists acting outside the central nervous system (CNS) is a promising therapeutic strategy for pain control that avoids deleterious central side effects such as apnea and addiction. In human clinical trials and rat models of inflammatory pain, peripherally restricted opioids have repeatedly shown powerful analgesic effects; in some mouse models however, their actions remain ...

Neurotrophins modulate the endogenous opioid system, but the underlying mechanisms are poorly understood. We observed an unexpected effect of neurotrophin signaling on the membrane trafficking of recombinant opioid receptors expressed in neurosecretory cells. Epitope-tagged delta opioid receptor (DOR) and mu opioid receptor (MOR) were differentially localized between surface and internal membra...

Sucrose ingestion has been shown to alleviate pain and distress in rats, human infants as well as adults. Sucrose induced analgesia is related to the reward value associated with its sweet taste. The sweet taste of sucrose is a stimulus for the activation of endogenous opioid pool. The opioids in turn modulate pain perception. It has been demonstrated in a number of animal and human studies tha...

Opioid receptors were shown to modulate a variety of cellular processes in the vertebrate central nervous system, including synaptic transmission. While the effects of opioid receptors on chemically mediated transmission have been extensively investigated, little is known of their actions on gap junction-mediated electrical synapses. Here we report that pharmacological activation of mu-opioid r...

To the Editor: Cannabinoids block pain responses in virtually every laboratory pain model tested. In models of acute or physiological pain, cannabinoids are highly effective against thermal, mechanical, and chemical pain, and are comparable to opioids in potency and efficacy.1 In models of chronic pain, cannabinoids exhibit efficacy in the modulation of both inflammatory2 and neuropathic pain.3...